Kingdom: Animalia Phylum: Chordata. MAMMALIA Mammals (formally Mammalia) are a class of vertebrate,...
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Kingdom: Animalia Phylum: Chordata. MAMMALIA Mammals (formally Mammalia) are a class of vertebrate, air-breathing animals whose females are characterized
MAMMALIA Mammals (formally Mammalia) are a class of vertebrate,
air-breathing animals whose females are characterized by the
possession of mammary glands while both males and females are
characterized by hair and/or fur, three middle ear bones used in
hearing, and a neocortex region in the brain. Some mammals have
sweat glands, but most do not.
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MAMMALIA 1. Mammals are divided into 21 groups. Scientists do
not yet agree on the exact number of mammal groups. some of the
better known mammal groups include Primates Marsupials Bats
Cetaceans Carnivores Lesser known mammals include the hyraxes
Monostremes Pangolins
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MAMMALIA 2. There are between 4,500 and 5,000 species of
mammals of all mammal groups. the most diverse are the mammal group
are: Rodents (1,700 species.) bats (977 species), primates (356
species), insectivores (365 species), marsupials (292 species).
Mammal groups with the fewest number of species: the aardvark (1
species), dugongs and manatees (4 species), flying lemurs (2
species).
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MAMMALIA 3. The first mammals appeared approximately 200
million years ago during the Jurassic Period. The ancestors of
mammals were a group of reptiles known as the therapsids. The first
true mammals to have evolved diverged from the therapsids during
the Jurassic Period. Of all the mammal groups alive today, the
monotremes are the oldest, followed by the marsupials. 4. Mammals
are tetrapods. Mammals have four limbs, a characteristic that
places them among the group of animals known as tetrapods. It
should be noted that although some mammals such as whales, dugongs,
and manatees have lost their hind limbs during the course of
evolution, they are tetrapods by descent. 5. Mammals are
warm-blooded. Mammals are warm-blooded or 'endothermic' which means
they generate their own internal heat.
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MAMMALIA 6. All mammals have hair. Hair is a defining
characteristic of mammals, no other organisms possess true hair and
all mammals have hair covering at least part of their body at some
time during their life. 7. Mammals are amniotes. Amniotes are a
terrestrial vertebrates whose eggs are characterized by having
several layers of protective membranes (the amnion, chorion and
allantois). Reptiles, mammals, and birds are all amniotes.
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MAMMALIA 8. The Cenezoic Era is the 'Age of Mammals'. The
Cenezoic Era (65 million years ago until the present day) is
considered to be the Age of Mammals because it represents the time
period during which mammals diversified and became the dominant
land vertebrates. 9. The largest mammal is the blue whale. The blue
whale is the largest mammal and is also the largest animal alive
today. It may even be the largest animal ever to have lived. Blue
whales weigh between 110160 tons (110176 tons) and mature
individuals measure in the range of 2030 m (6698 ft).
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MAMMALIA 10. The smallest mammal is the bumblebee bat. The
bumblebee bat, also called the Kitti's hog-nosed bat, is the
smallest of all mammals, measuring just over an inch in length and
weighing a mere 2g. The bumblebee bat is a vulnerable species that
inhabits limestone caves in Thailand and Burma.
MONOSTREMES From the Greek word monos means single, trema means
hole are mammals that lay eggs Divided into the orders 1.Platypoda
-the platypus along with its fossil relatives 2.Tachyglossa -the
echidnas, or spiny anteaters
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MONOSTREMES Platypus Fossil range : Late Cretaceous to Recent
Echidnas(ant eaters) Fossil range: MioceneRecent
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MARSUPIALS are an infraclass of mammals, characterized by a
distinctive pouch (called the marsupium), in which females carry
their young through early infancy.
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MARSUPIALS Kangaroo Fossil record: Early Cretaceous to
recent
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PLACENTA Also known as Eutheria, Greek: true/good beasts is a
group of mammals consisting of placental mammals plus all extinct
mammals that are more closely related to living placentals (such as
humans) than to living marsupials (such as kangaroos) One of the
major differences between placental and non-placental eutherians is
that placentals lack epipubic bones, which are present in all other
fossil mammals and living mammals (monotremes and marsupials).
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PLACENTA Fossil of Eomaia,Eomaia the oldest known
eutherian
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MAMMALIA Most mammals, including the six largest orders, belong
to the placental group. The six largest orders, in descending
order, 1. Rodentia (rodents) 2. Chiropeta (bats) 3. Soricomorpha
(shrew-form, moles) 4. Carnivora (dogs, cats, bears) 5.
Cetartiodactyla (dolphin, whale) 6. Primates (humans, apes)
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RODENTIA
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CHIROPTERA No mammals other than bats have true wings and
flight
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SORICOMORPHA
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CARNIVORA
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CETARTIODACTYLA
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PRIMATES
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EVOLUTION
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MAMMALIAFORMES Mammaliaformes (mammal-shaped) is a clade that
contains the mammals and their closest extinct relatives.
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MAMMALIAFORMES
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ADELOBASILEUS Adelobasileus cromptoni is a species of an
extinct genus of proto-mammals from the Late Triassic (Carnian),
about 225 million years ago. It is known only from a partial skull
recovered from the Tecovas formation in western Texas.
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SINOCODON Ancient proto-mammal that appears in fossil record in
the late Triassic period, about 208 million years.
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MORGANUCUDON Morganucodon (Glamorgan tooth") is an early
mammalian genus which lived during the Late Triassic. "It was a
small animal with a skull 2-3 cm in length and a presacral body
length of about 10 cm [4 inches]. In general appearance it would
have looked like a shrew or mouse
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MORGANUCUDON
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DOCODONTA Docodonta is an order of extinct proto- mammals that
lived during the mid- to late- Mezosoic era. Their most
distinguishing physical features were their relatively
sophisticated set of molars, from which the order gets its name. In
the fossil record, Docodonta is represented primarily by isolated
teeth and bits of jawbones.
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DOCODONTA
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HADROCODIUM Hadrocodium wui is an extinct basal mammal species
that lived during the Lower Jurassic. Hadrocodium was a mere 3.2 cm
(1.35 in) in length (about 2 grams), and is one of the smallest
mammals of either the Mesozoic or Cenozoic eras.
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MAMMALIA
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EVOLUTION Comparison reveals that, although placental and
marsupial mammals formed seperate lineages, they still evolved
similar adaptations. In some cases, placental and marsupial mammals
physically resemble each other: the pouched marsupial mouse and the
harvest mouse, the marsupial mole and the common mole, the
marsupial wombat and the marmot, the tasmanian wolf and the wolf.
Definitions The discussion above illustrates the following
evolutionary concepts: divergent evolution-occurs when a single
group of organisms splits into two groups and each group evolves in
increasingly different directions parallel evolution-occurs when a
group of organisms evolve into two distinct but similar lineages
and continue to adapt in similar ways for a long period of time,
often in response to a similar environment convergent
evolution-evolutionary change in two or more unrelated organisms
that results in the independent development of similar adaptations
to similar environmental conditions
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ANATOMY and MORPHOLOGY Skeletal system The majority of mammals
have seven cervical vertebrae (bones in the neck); this includes
bats, giraffes, whales, and humans. The few exceptions include the
manatee and the two-toed sloth, which have only six cervical
vertebrae, and the three-toed sloth with nine cervical
vertebrae.
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ANATOMY and MORPHOLOGY Respiratory system The lungs of mammals
have a spongy texture and are honeycombed with epithelium having a
much larger surface area in total than the outer surface area of
the lung itself. The lungs of humans are typical of this type of
lung.
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ANATOMY and MORPHOLOGY Nervous system All mammalian brains
possess a neocortex, a brain region that is unique to mammals.
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FEEDING Most mammals have teeth, although some, like the baleen
whales, do not. Since mammals range widely in habitat and food
preferences, they have a wide range in feeding styles and
preferences. In marine mammals, whales feed using teeth or baleen,
and on a variety of prey, including small fish, crustaceans and
sometimes other marine mammals. Pinnipeds feed using teeth, usually
eating fish and crustaceans. Sirenians also have teeth, although
they also use the power of their strong lips when grasping and
ripping aquatic vegetation.
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REPRODUCTION Mammals reproduce sexually and have internal
fertilization. All marine mammals are placental mammals, meaning
they give birth to live young, and the unborn young are nourished
in the mother's uterus by an organ called the placenta.